The present invention relates to fluid connectors and, more particularly, to the sealing interconnection of such connectors with tubing end forms and, more particularly still, the use of spin welding to effect such interconnection.
Quick connect couplings have been widely used in the U.S. Automobile industry for many years. Although applicable in numerous applications, quick connectors are typically employer in fuel system and vapor recovery systems. The simplest and most cost effective design is the plastic housing female type quick connector releasably mated to a metal male tube endform. The opposite end of the female housing most typically defines a stem having a member of axially spaced barbs formed on the outer circumferential surface thereof and a nylon or plastic tubing endform pressed there over. Such an arrangement is described in U.S. Pat. No. 5,542,712.
In fluid handling systems, it is imperative that the connectors used have male and female portions properly coupled together. A faulty connector enables an associated system to leak fluid. This can be particularly disadvantageous when the system is under pressure and the leaking connector expels the pressurized fluid. Furthermore, recent Federal legislation has mandated significantly reduced hydrocarbon emissions from automotive fuel and vapor recovery systems. Conventional quick connectors, although effective to mechanically maintain tubing endforms in assembly with their associated connector bodies, have not adequately addressed the federal requirements. Also, the materials employed, typically nylon 12, do not provide sufficient resistance to the permeation of hydrocarbons therethrough.
The permeation problem been addressed in part through the development of co-extruded multi-layer plastic tube containing two or more discrete layers of different types or formulations of plastic, one of which is specifically designed to provide an effective permeation layer, blocking the escape of hydrocarbons from the system. In general, the most successful multi-layer tubing employs a relatively thick outer layer composed of a material resistant to the exterior environment. The innermost layer is thinner and is composed of a material which is chosen for its ability to block defusion of materials, such as hydrocarbons, alcohols and other materials present in fuel blends, to the outer layer and may have a degree of electrical conductivity sufficient to dissipate static charges generated by the flow of fluid therein. To date, it has been extremely difficult to obtain satisfactory lamination characteristics between dissimilar polymer layers. Thus, the use of one or more intermediate layers for bonding the inner and outer layers has been proposed.
The use of multi-layer tubing in fuel related applications has been problematic inasmuch as the tubing endform necessarily exposes the lamina ends of the inner and outer layers as well as any intermediate layers to either the system fuels and vapors or the equally harsh exterior environment. Such exposure tends to degrade the bonding between the various layers, causing delamination or separation of the layers, resulting in loss of system integrity, fuel contamination and even blockage of fluid flow.
A related problem stems from dual aspects of commercially available quick connect devices, to wit: high volume and low sale price frequently necessitating the use of inexpensive, somewhat pliable materials, and complex contours of extremely small inter-fitting components. These aspects collectively increase the likelihood of misassembly. High volume production techniques, including automated assembly tends to aggravate the problem wherein misassembly or impermissible dimensional variations of the components is difficult to detect. Excessive dimensional tolerance stack-up can result in low pull-apart characteristics between the barbed stem and the plastic tube and produce leakage. Misassembly, such as failure to include a 0-ring, can also result in leakage. In the case of multi-layer tubes, dimensional and/or adhesive problems can result in mechanical delamination upon insertion of the tube over the barbed stem. Finally, mono-wall plastic tube or multi-layer structures with low hoop strength can relax over time or at elevated temperatures, resulting in leaking or weeping of fluid.
To create a secure spin weld between a housing and an endform or tube, it is necessary that the housing or connector and the tube be of compatible materials. This has proven difficult where the connector is formed of a plastic and the tube of metal as well as situations where the connector housing is formed of metal and the tube of plastic. While attempts have been made to adhesively join a connector housing and a tubular endform where the tubular housing and the endform are formed of dissimilar materials, it is believed that further improvements can be made to fluidic couplings to ensure a secure, leak free, spin weld in a multi-part fluid coupling where the coupling components are formed of dissimilar materials not normally suited for spin welding.
The present invention is a spin welded fluid coupling which provides a spin weld join between first and second fluid carrying components.
In one aspect, the present invention is a method of forming a fluid coupling between first and second fluid carrying components. The method comprises the steps of forming an open ended, annular recess in one end of the first component, fixing a bonding material on a surface of the first recess in the spin weld compatible with the material of the first and second components, inserting the second component into the recess in the first component, and spin welding the first and second components causing the bonding material to sealingly join the first component to the second component.
In another aspect, the present invention is a fluid coupling formed of spin weld joined first and second fluid carrying components. The coupling includes a first component formed of a body having a through bore extending from a first end, a second component having a through bore extending from a first end, an open ended recess extending from the first end of the first component, a spin weld inducing bonding material layer disposed on at least one surface of the recess in the first component in the recess to spin weld join the first component to the second component.
The spin weld fluid coupling and method of making the same of the present invention provides a spin weld coupling between two fluid carrying components which uniquely enables the use of materials forming the first and second components which were previously too dissimilar to allow spin welding, to be spin welded together in a secure, leak-free joint. The unique use of a bonding material spin weld compatible with the materials forming the first and second components at the interface between the first and second components induces the spin weld between the dissimilar materials forming the first and second components despite the dissimilar materials.
The bonding material may be varied so as to be compatible with many different types of materials forming the first and second components to enable a metal endform, a plastic coated metal endform, or a plastic endform to be spin welded to a connector body or component formed of a plastic or a completely dissimilar material.